The invention relates to a power generator system for aircraft, and more particularly for an airplane, the system using a fuel cell.
In an airplane, the electricity needed for in-flight operation of the various pieces of electrical equipment is commonly supplied by one or more generators associated with engines of the airplane. With gas turbine engines, it is known to use starter/generators (S/Gs) for this purpose. They are mechanically coupled to a shaft of the turbine via a gearbox and they operate either as an electricity generator while in flight or else as an electric motor for starting. An auxiliary power unit (APU) supplies electricity, in particular on the ground, when the airplane engines are not running. Commonly an APU comprises a gas turbine driving a generator.
Since electricity is becoming ever more preferred over hydraulic power for actuating equipments of airplanes and of their motors, there is a need for producing ever increasing amounts of electricity on board airplanes.
To satisfy this increasing need without increasing the number and the power of generators such as S/Gs, proposals have been made to use a fuel cell in an APU. Reference can be made to document CA 2 427 448 which describes an electricity production system including a solid oxide fuel cell (SOFC). The cell receives a hydrocarbon fuel and compressed air coming from a compressor, and it produces direct current (DC) electricity together with a flow of hot gas under pressure. A turbine is fed with the gas flow and drives the compressor.
The assembly comprising the SOFC, the turbine, and the compressor operates in a manner similar to a conventional combustion gas turbine, with the SOFC taking the place of the combustion chamber, while also producing electricity without any polluting emission of nitrogen oxides (NOx).